1. Field of the Invention
The present invention generally relates to brittle non-metallic workpieces with through holes and methods for making same.
2. Discussion of the Related Art
For various purposes, a through hole is usually defined in workpieces made of glass or other brittle non-metallic materials. A typical process of making a hole in a glass substrate will be described using a conventional method as example. Firstly, a grinding machine including at least one grindstone is provided. The grindstone is substantially a hollow cylinder with two openings. A contour of the grindstone corresponds to that of the through hole. Secondly, the grindstone is placed on a first predetermined position of a first surface of the glass substrate. The grindstone is driven by a driving device, such as a motor, to gradually grind into the glass substrate. When a grinding crack extends through a half thickness of the glass substrate, the grindstone stops grinding the glass substrate. Thirdly, the glass substrate is turned over, and the grindstone is placed on a second predetermined position corresponding to the first predetermined position. Then, the grindstone is driven by the driving device, to grind into the glass substrate until the grinding crack extends through the glass substrate. An excess portion inside the grinding crack is separated and removed from the glass substrate, thereby forming a through hole in the glass substrate.
However, since the through hole of the glass substrate is formed via grinding, an inner surface for forming the through hole has many burrs and microcracks. The microcracks result in weakening the strength of the glass substrate.
Therefore, a brittle non-metallic workpiece with a through hole which has no aforementioned shortcomings is desired. A new method for such workpiece is also desired.